(1) Field of the Invention
The present invention relates to nonplanar acoustic arrays and more particularly to an acoustic array which conforms closely to the curved laminar flow surface of a low drag underwater shape thereby maximizing available nearby internal nose volume while providing new capabilities and improved array performance.
(2) Description of the Prior Art
Present torpedo acoustic arrays are generally planar. Planar arrays however present many problems which place undue restrictions on torpedo diameter, nose shape, volume utilization, and array capability and performance. This is especially true where the torpedo nose must present a low drag laminar flow shape. A standard forward-looking planar array should be as large in diameter as the torpedo diameter will allow in order to provide maximum array gain. Unfortunately, for a curved, low drag nose this means the array must be positioned far away from the tip of the nose resulting in a large wasted forward volume. Also a forward-looking array is not very efficient when looking at angles far from the straight ahead boresight axis. In order to solve these problems, an array comprising two generally side-looking planar arrays has been constructed (see co-pending U.S. Navy patent application Ser. No. 237,549) where the planar array faces are generally parallel to the curved torpedo nose. This approach, while providing an improvement over the forward-looking array, does not solve the problem of maximizing useful available internal volume. In addition the side-looking planar array requires the use of thick acoustic windows in the pressure hull which produce undesirable refractive effects. Also, although the number of array elements has been increased with the side-looking planar array, the limitation of array elements to a planar surface places an overly restrictive bound on potential array aperture especially side-to-side aperture. The instant invention avoids these problems by providing an array that closely conforms to the nonplanar surface of the nose of a low drag torpedo.